The invention relates to a display unit and a method of preparing the surface of display unit such as a traffic sign.
Conventional traffic signs often have reflective surfaces so that the signs can be clearly seen even though it is dark. More particularly, the reflective surfaces reflect back the light emitted from cars passing the traffic signs. However, the effectiveness of the reflective surfaces can be severely reduced by dirt and wear over time. Conventional reflective traffic signs are often coated with a plastic coating. The plastic coating often cracks over time because the polymer coating dries which further reduces the reflective properties of conventional traffic signs.
To overcome this problem, some municipalities and other maintenance organizations use cleaning crews that drive along the highways and other roads to clean the traffic signs. This is a very slow and labor intensive process. The vehicles used by the cleaning crew themselves may also be a traffic hazard due to the numerous stops made by such vehicles. In many instances, the traffic signs are never cleaned and the reflectiveness of the traffic signs is reduced to unacceptably low levels. This increases the risk of injury to users of the road because they cannot see the signs properly when it is dark outside.
There is a need to improve the effectiveness of the reflective traffic signs and to reduce the need for cleaning the traffic signs. There is also a need to increase the product life cycle of the reflective traffic signs.
The present invention solves some of the above mentioned problems. The method comprises applying a first compound to the polymeric coating and grinding the first compound on the polymeric coating to even out a surface of the polymer coating. A second compound may then applied to the polymeric coating and ground on the polymeric coating to form a protective coating on the polymeric coating with the second compound. The protective coating is cleaned and a first polishing compound is applied to an oscillating polishing machine to polish the protective coating with the first polishing compound. A second polishing compound is then applied on the polishing machine and the protective coating is polished with the second polishing compound to form a polishing surface coating on the protective coating so that the retro reflection is at least 11 candela/m2/lux.